Divides resources into teaching materials, history content, and best practices (good combination of what to teach and how to teach). Try clicking on the Elementary School Teachers link in the lower right corner.

Lessons on astronomy, earthquakes, erosion, maps, plate tectonics, rocks and minerals, volcanoes, water, and weather. Most of the lessons are written at a secondary level. Some lessons link out to other sites, some are proprietary to the site.